Estimating migration costs for migrating logical partitions within a virtualized computing environment based on a migration cost history

ABSTRACT

Responsive to a hypervisor determining that insufficient local resources are available for reservation to meet a performance parameter for at least one resource specified in a reservation request for a particular logical partition managed by the hypervisor in a host system, the hypervisor identifies another logical partition managed by the hypervisor in the host system that is assigned at the least one resource meeting the performance parameter specified in the reservation request. The hypervisor estimates a first cost of migrating the particular logical partition and a second cost of migrating the another logical partition to at least one other host system communicatively connected in a peer-to-peer network based on at least one previously recorded cost stored by the host system of migrating a previous logical partition to the at least one other host system.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of commonly assigned U.S. patentapplication Ser. No. 13/551,521, filed Jul. 17, 2012, which is acontinuation of U.S. patent application Ser. No. 13/325,487, filed Dec.14, 2011, which are both hereby incorporated herein by reference.

BACKGROUND

1. Technical Field

This invention relates in general to computing environments and moreparticularly to maintaining a migration cost history by each host systemin a virtualized computing environment and efficiently estimatingmigration costs of multiple logical partitions at each host system basedon the migration cost history to enable the host system to select amigration candidate based on estimated migration costs.

2. Description of the Related Art

In a virtualized host system, a hypervisor may manage the allocation ofresources into one or more logical partitions, or virtual machine, eachrepresenting a separate logical grouping of resources assigned to aninstance of an operating system, upon which an application or workloadruns. When an application running in a particular logical partitionsends a memory allocation request to an operating system in a logicalpartition, if the logical partition cannot satisfy the resource requestwith free memory, the operating system rejects the resource request orsatisfies the resource request using a performance tradeoff of pagingitems to disk, which slows down memory accesses.

BRIEF SUMMARY

In view of the foregoing, there is a need for a method to enable ahypervisor of a host system receiving a reservation request for aparticular logical partition managed by the hypervisor in the hostsystem to manage the allocation of resources to an application bymigrating the logical partition for the application or by migratinganother logical partition to free resources to meet the reservationrequest.

In one embodiment a method for managing requests for resources isdirected to, responsive to a hypervisor determining that insufficientlocal resources are available for reservation to meet a performanceparameter for at least one resource specified in a reservation requestfor a particular logical partition managed by the hypervisor in a hostsystem, identifying another logical partition managed by the hypervisorin the host system that is assigned at the least one resource meetingthe performance parameter specified in the reservation request. Themethod is directed to estimating, by the hypervisor, a first cost ofmigrating the particular logical partition and a second cost ofmigrating the another logical partition to at least one other hostsystem communicatively connected in a peer-to-peer network based on atleast one previously recorded cost stored by the host system ofmigrating a previous logical partition to the at least one other hostsystem. The method is directed to selecting, by the hypervisor, one ofthe particular logical partition and the another logical partition as amigration candidate based on a comparison of the first cost with thesecond cost, wherein the hypervisor negotiates for offers to migrate themigration candidate to the at least one other host system. The method isdirected to, responsive to selecting a remote host system from among theat least one other host system to migrate the migration candidate to,calling, by the hypervisor, a cost estimator of the host system tocreate a migration header. The method is directed to selecting, by thecost estimator, a selection of most recent previously recorded migrationcosts by the host system for a target logical partition and for theremote host system. The method is directed to encoding, by the costestimator, a migration data header with the selection of most recentpreviously recorded migration costs. The method is directed to encoding,by the hypervisor, the migration candidate with the migration dataheader, wherein the remote host system receives the migration candidatewith the migration data header, removes the migration data header fromthe migration candidate, and records the selection of most recentlyprevious recorded migration costs for the target logical partition andfor the remote host system for estimating the cost of migrations fromthe remote host system.

In another embodiment, a logically partitioned host system havingmultiple logical partitions of pools of virtualized resources and anoperating system operating in each of the logical partitions, comprisesa hypervisor operative on the host system, wherein the host systemcomprises at least one memory and at least one processor coupled to thememory, to manage the logical partitions of pools of virtualizedresources and operative, responsive to determining that insufficientlocal resources are available for reservation to meet a performanceparameter for at least one resource specified in a reservation requestfor a particular logical partition managed by the hypervisor in the hostsystem, to identify another logical partition from among the logicalpartitions that is assigned the at least one resource meeting theperformance parameter specified in the reservation request. Thelogically partitioned host system comprises the hypervisor operative toestimate a first cost of migrating the particular logical partition anda second cost of migrating the another logical partition to at least oneother host system communicatively connected in a peer-to-peer networkbased on at least one previously recorded cost stored by the host systemof migrating a previous logical partition to the at least one other hostsystem. The logically partitioned system comprises the hypervisoroperative to select one of the particular logical partition and theanother logical partition as a migration candidate based on a comparisonof the first cost with the second cost, wherein the hypervisornegotiates for offers from the at least one other host system to migratethe migration candidate to the at least one other host system. Thelogically partitioned system comprises the hypervisor, responsive toselecting a remote host system from among the at least one other hostsystem to migrate the migration candidate to, operative to call a costestimator of the host system to create a migration header. The logicallypartitioned system comprises the cost estimator operative to select aselection of most recent previously recorded migration costs by the hostsystem for a target logical partition and for the remote host system.The logically partitioned system comprises the cost estimator operativeto encode a migration data header with the selection of most recentpreviously recorded migration costs. The logically partitioned systemcomprises the hypervisor operative to encode the migration candidatewith the migration data header, wherein the remote host system receivesthe migration candidate with the migration data header, removes themigration data header from the migration candidate, and records theselection of most recently previous recorded migration costs for thetarget logical partition and for the remote host system for estimatingthe cost of migrations from the remote host system.

In another embodiment, a computer program product for managing requestsfor resources is tangibly embodied in a computer-readable storagemedium. The computer program product comprises computer executableinstructions which cause a computer to, responsive to a hypervisordetermining that insufficient local resources are available forreservation to meet a performance parameter for at least one resourcespecified in a reservation request for a particular logical partitionmanaged by the hypervisor in a host system, identify another logicalpartition managed by the hypervisor in the host system that is assignedat the least one resource meeting the performance parameter specified inthe reservation request. The computer program product comprises computerexecutable instructions which cause a computer to estimate, by thehypervisor, a first cost of migrating the particular logical partitionand a second cost of migrating the another logical partition to at leastone other host system based on at least one previously recorded coststored by the host system of migrating a previous logical partition tothe at least one other host system. The computer program productcomprises computer executable instructions which cause a computer toselect, by the hypervisor, one of the particular logical partition andthe another logical partition as a migration candidate based on acomparison of the first cost with the second cost, wherein thehypervisor negotiates for offers to migrate the migration candidate tothe at least one other host system. The computer program productcomprises computer executable instructions which cause a computer to,responsive to selecting a remote host system from among the at least oneother host system to migrate the migration candidate to, call, by thehypervisor a cost estimator of the host system to create a migrationheader. The computer program product comprises computer executableinstructions which cause a computer to select, by the cost estimator, aselection of most recent previously recorded migration costs by the hostsystem for a target logical partition and for the remote host system.The computer program product comprises computer executable instructionswhich cause a computer to encode, by the cost estimator, a migrationdata header with the selection of most recent previously recordedmigration costs. The computer program product comprises computerexecutable instructions which cause a computer to encode, by thehypervisor, the migration candidate with the migration data header,wherein the remote host system receives the migration candidate with themigration data header, removes the migration data header from themigration candidate, and records the selection of most recently previousrecorded migration costs for the target logical partition and for theremote host system for estimating the cost of migrations from the remotehost system.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The novel features believed characteristic of one or more embodiments ofthe invention are set forth in the appended claims. The one or moreembodiments of the invention itself however, will best be understood byreference to the following detailed description of an illustrativeembodiment when read in conjunction with the accompanying drawings,wherein:

FIG. 1 is a block diagram illustrating one example of a virtualizedcomputing environment in which a hypervisor manages negotiations forresources meeting at least one performance parameter, including qualityof service, within the host system and among remote host systems for anapplication from an application initiated request for resourcesspecifying the performance parameter;

FIG. 2 is a block diagram illustrating one example of a broker agent formanaging negotiations for resources meeting performance parameters in avirtualized computing environment;

FIG. 3 is a block diagram illustrating one example of a reservationtable entry for a reservation request mapped to a particular tablewithin managed resource tables;

FIG. 4 is a block diagram illustrating one example of the one or moretypes of policy rules that may be specified in a policy applied by thebroker agent;

FIG. 5 is a block diagram illustrating a mediator called by a brokeragent for managing the tracking of incoming communications from remotehost systems and outgoing communications to remote host systems;

FIG. 6 is a block diagram illustrating one example of a ensembleincluding multiple virtualized host systems, each managed by a separatehypervisor instance;

FIG. 7 is a block diagram illustrating one example of a broker agentmanaging local memory allocations and logical partition migrations, toprovide memory meeting the quality of service requirements of one ormore workloads;

FIG. 8 is a block diagram illustrating one example of a cost estimatorimplemented for estimating costs for migrating logical partitions basedon historical data captured from previous migrations of logicalpartitions;

FIG. 9 is a block diagram illustrating one example of a schematic of acomputer system in which the present invention may be implemented;

FIG. 10 is a high level logic flowchart illustrating one example of aprocess and program for managing application initiated negotiations forresources with a specified performance parameter;

FIG. 11 is a high level logic flowchart illustrating one example of aprocess and program for a negotiation interface of an operating systemmanaging application initiated negotiations for resources meetingperformance parameters;

FIG. 12 is a high level logic flowchart illustrating one example of aprocess and program for a hypervisor managing two levels of negotiationsfor resources based on an application initiated negotiation forresources meeting performance parameters specified by the application;

FIG. 13 a-13 b is a high level logic flowchart illustrating one exampleof a process and program for a broker agent of a hypervisor managingapplication initiated negotiations for local or remote resources meetingperformance parameters specified by the application;

FIG. 14 is a high level logic flowchart illustrating a process andprogram for managing application initiated negotiations for resourcesfrom a legacy application or other application that does not specify aperformance parameter in a resource request;

FIG. 15 is a high level logic flowchart illustrating a process andprogram for a partition controller receiving an LPAR migration andcalling a cost estimator with the migration history for the LPARmigration for storing in a cost estimator history table;

FIG. 16 is a high level logic flowchart of a process and program forupdating a history table with estimated and current costs for logicalpartition migrations gathered during negotiations by a broker agent;

FIG. 17 is a high level logic flowchart of a process and program for apartition controller requesting migration header history for an LPAR tobe migrated; and

FIG. 18 is a high level logic flowchart of a process and program for acost estimator estimating the cost for migration of an LPAR.

DETAILED DESCRIPTION

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. It will be apparent, however, toone skilled in the art that the present invention may be practicedwithout these specific details. In other instances, well-knownstructures and devices are shown in block diagram form in order to avoidunnecessarily obscuring the present invention.

In addition, in the following description, for purposes of explanation,numerous systems are described. It is important to note, and it will beapparent to one skilled in the art, that the present invention mayexecute in a variety of systems, including a variety of computer systemsand electronic devices operating any number of different types ofoperating systems.

With reference now to the Figures, and in particular with reference nowto FIG. 1, a block diagram illustrates one example of a virtualizedcomputing environment in which a hypervisor manages negotiations forresources meeting at least one performance parameter, including qualityof service, within the host system and among remote host systems for anapplication from an application initiated request for resourcesspecifying the performance parameter.

In the example, a virtualized computing environment 100 may include oneor more types of virtualized environments, including, but not limitedto, a workload distribution environment, a cloud computing environment,a grid environment, a cluster environment, and other types of computingenvironments implementing one or more virtualization layers using one ormore types of virtual machines or systems for managing virtualizedresources. In one example, one or more host systems are identifiedwithin virtualized system environment 100, where each host system isvirtualized by including one or more logical partitions or virtualmachines, such as logical partition 102, managed by a hypervisor 120 orother firmware for managing a virtualization layer, such as avirtualization layer of resources virtualized into partitioned, logicalpools of resources. In one example, logical partition 102 represents apartitioned, virtual group of one or more hardware, software, andfirmware resources currently configured in logical partition 102 byhypervisor 120 from one or more computing systems. In one embodiment, ahost system refers to a system in which a hypervisor, such as hypervisor120, manages at least one logical partition, and the remote host systemsor other host systems refers to other virtualized systems managed byother hypervisors instances independent of hypervisor 120.

Hypervisor 120 manages at least one of partitioning of resources tological partitions, the sharing of resources between logical partitions,the dynamic movement of resources between logical partitions, thedistribution of workloads across logical partitions, the movement ofworkloads from one partition to another logical partition, and themigration of workloads and partitions from one host system to anotherhost system within virtualized system environment 100. In addition,hypervisor 120 may communicate with other hypervisors of other hostssystems organized within virtualized system environment 100 forpeer-to-peer communication or may communicate with other host systemsthrough a management interface.

In one example, operating system 108 within logical partition 102manages requests for resources from application 104 and manages theallocation of specific resources for application 104. One of ordinaryskill in the art will appreciate that operating system 108 may representa kernel and may include a resource management unit specified formonitoring resource usage within logical partition 102, requestingadditional resources from hypervisor 120, and managing the use ofresources within logical partition 102.

In one embodiment, application 104 submits one or more resourcerequests, such as resource request 106, to operating system 108,specifying one or more resource requirements for application 104.Application 104 may represent one or more instances of an application ormay represent one or more workloads scheduled to run or running on anapplication.

In one embodiment, resource request 106 may request a lease of one ormore types and amounts of resources and may specify one or moreperformance parameter requirements, as illustrated at reference numeral150. Performance parameters may include, but are not limited to, a leasestart time, a lease duration, a desired quality of service (QoS), aresource locality, and a cost. In one example, a lease start time mayspecify “now” and may specify one or more future times. In one example,a lease duration may specify a particular time or may specify a workloadestimation. In one example, a desired QoS may specify a particular typeof resource, a particular option for a resource, or other values thatindicate a quality of service for a particular type of resource. In oneexample, a resource locality may specify “local” for a local hostsystem, “global” for use of local host systems and other host systems,“migration” for use of other host systems, and other indicators limitingresource locations. In one example, “cost” may specify a price, aparticular number of units of usage, or other value that indicates acharge for use of a resource. In another example, “cost” may alsospecify a cost profile that should be applied to satisfy a resourcerequest.

In the example, operating system 108 sends a request response 116 thatspecifies whether resource request 106 is locally granted, meeting thespecified performance parameters, or whether resource request 106 islocally declined. In addition, response to request 116 may include, if arequest is declined, alternate options 118, specifying recommendedadjustments for one or more of the performance parameters or globaloffers 154 including one or more offers for migrating application 104 toa remote host system.

In one example, for operating system 108 to handle resource request 106as a negotiation to lease resources from application 104, operatingsystem 108 includes a negotiation interface (NI) 110 that provides anapplication programming interface (API) and controller for processingresource request 106 from application 104, where resource request 106includes resource specifications and performance parameters 150. NI 110receives resource request 106, filters resource request 106 to determinewhether resource request 106 is a request to initiate a negotiation forresources meeting performance parameters, and formats resource request106 into a resource reservation request format accepted by hypervisor120, as illustrated by reservation (res) request 160. By application 104specifying resource request 106 to call negotiation interface 110,application 104 is enabled to initiate a negotiation for resources, bothlocally and remotely, that meet specific performance parameters as setby application 104, rather than ceding to the performance parametersselected by operating system 108, hypervisor 120, or other component.

In one example, negotiation interface 110 of operating system 108receives resource request 106 and operating system 108 queries a brokeragent 126 with res request 160 to negotiate for local resources to bemoved to logical partition 102 meeting the performance parameters ofresource request 106 from the host system. Broker agent 126 may consultlocal or internal tables for resources managed in the host system todetermine the availability of resources within the host system. Asillustrated, if broker agent 126 determines that resource request 106can be satisfied locally, then operating system 108 schedules areservation of the available resources, illustrated as a local systemlease 124, in host system 132 for resource request 106 and returns areservation (res) response 162 indicating the granting of local systemlease 124. In addition, hypervisor 120 coordinates with operating system108 to transfer resources to fulfill local system lease 124 during thelease period for the duration of the lease. Operating system 108 returnsrequest response 116 to application 104 indicating the resource requesthas been locally granted and allocates the resources leased to logicalpartition 102 during the lease period, to application 104.

In addition, in one example, if the performance parameters in resourcerequest 106 specify a locality that includes remote host resources andif broker agent 126 determines that resource request 106 cannot besatisfied within the host system, broker agent 126 makes a peer-to-peerhypervisor call 130 that sends resource request 106 directly to one ormore hypervisors of other, remote host systems. Broker agent 126 waitsfor a period of time for responses by other host systems to thehypervisor call, collects any responses 166 to the hypervisor call, andevaluates any responses from other host systems to the hypervisor call.Broker agent 126 selects one or more of the responses from other hostsystems as the best offer for migrating application 104 and passes theoffer for migrating application 104 to operating system 108 in resresponse 162. Operating system 108 returns the offer to application 104in global offers 154. If application 104 accepts the offer for migratingapplication 104, application 104 calls negotiation interface 110 toaccept the offer, as illustrated by offer acceptance 152, operatingsystem 108 passes the offer acceptance to broker agent 126 in resrequest 160, and broker agent 126 begins brokering the migration ofapplication 104 to the remote host system with the accepted offer. Inone example, application 104 may initially submit resource request 106that automatically authorizes migration, and broker agent 126 willautomatically start migrating application 104 to the remote host systemwith the selected offer.

Broker agent 126 may determine, from among responses 166, the one ormore responses with the best offers from other host systems, accordingto one or more policies, and establish a lease of the resources on theother host system, illustrated as global system lease 128. Broker agent126 controls migration of application 104 alone or of logical partition102 to the other host system during the least time specified in globalsystem lease 128.

Broker agent 126 may also determine, if one or more of the local hostsystem and other host systems cannot satisfy one or more of theperformance parameters in resource request 106, whether alternateresources are available that do not meet all the performance parametersin resource request 106, but reduce or omit one of performance parametervalues. If alternate resources are available that do not meet all theperformance parameters in resource request 106, operating system 108 mayidentify one or more options for performance parameters to use thealternate resources and return the options as one or more alternateoptions 118 to return to application 104 with response to request 116.In one example, alternate options 118 may include codes designated byoperating system 108 to identify one or more parameters that need to beadjusted or errors in the resource request.

When application 104 receives alternate options 118 or global offers 154in response to resource request 106, application 104 may accept globaloffers 154 or adjust the performance parameter requirements and resubmitresource request 106. In one example, application 104 may adjust theperformance parameter requirements for a resource lease according toalternate options 118. In another example, application 104 may adjustthe performance parameter requirements for a resource lease in view ofalternate parameter recommendations, but also according to negotiationpolicies determined by application 104. For example, if alternateoptions 118 return a recommendation to reduce a quality of service valueby 25%, application 104 may determine, based on negotiation policies, toreduce a quality of service value by a maximum amount of 10%, but toincrease a value of another factor, such as cost or locality, in aresubmitted resource request. By application 104 receiving alternateoptions 118 or global offers 154, adjusting performance parameters inresource request 106 setting offer acceptance 152, and callingnegotiation interface 110 with resource request 106, application 104 isenabled continue to negotiate within the local host system and withother host systems, for resources meeting performance requirements, asspecified by application 104.

In addition, prior to broker agent 126 making hypervisor call 130,broker agent 126 may determine whether there are one or more otherapplications, identified within other logical partitions (LPARs)operating in the host system, which if the other LPAR were migrated toone of the other host systems, would release sufficient system resourcesof the host system to allow the host system to schedule resources forlocal system lease 124 for logical partition 102, in response toresource request 106. If there are one or more other LPARs operating inthe host system, which if migrated to one of the other host systems,would release sufficient system resources of the host system to allowthe host system to schedule local system lease 124 for logical partition102, then broker agent 126 may send cost requests to a cost estimator170 requesting estimated costs for migrating each of logical partition102 and the other LPARs. Cost estimator 170 returns an estimated costfor migrating each of logical partition 102 and the other LPARs, andbroker agent 126 selects which logical partition to migrate based onpolicies, such as choosing to migrate the logical partition with thelowest estimated migration cost. Once broker agent 126 selects which oneor more logical partitions to attempt to migrate for the negotiationbased on estimated migration costs, broker agent 126 sends hypervisorcall 130 to the other host systems for the selected one or more logicalpartitions.

In the example, cost estimator 170 collects data related to migrationcosts of logical partitions to and from the host system from responses166, global system lease 128, and broker agent 126, and stores thecollected historical data in a history table for use in estimating costsof future logical partition migrations for broker agent 126. Inaddition, in the example, cost estimator 170 may select data from thehistory table that is relevant to the migration of an application or alogical partition out of the host system and attach the relevanthistorical cost data to a migration data header for the migrating LPAR,where the other host system receiving the migrating LPAR strips themigration data header from the migrating LPAR and also stores therelevant historical cost data for the LPAR migration in a history tablefor use by the cost estimator of the remote host system for calculatingfuture LPAR migration cost estimates. By cost estimator 170 locallycollecting and distributing historical cost data for LPAR migrations toand from the host system, cost estimator 170 is able to efficientlyestimate costs for future LPAR migrations without requiring networkbandwidth and other resource usage to query other host systems forestimated costs and cost estimator 170 is able to efficiently updateother host systems in the peer-to-peer network with historical cost datafor LPAR migrations.

In one example, migration costs collected by cost estimator 170 arebased on migration cost inputs that may include, but are not limited to,network latency between systems, processor speeds of systems, processorutilization on each system, and a memory footprint of the partition.Cost estimator 170 collects the historical cost data for LPAR migrationsfrom estimated values of the migration cost inputs prior to migrationand real values of the migration cost inputs after the migration.

In the example, one or more components within a host system may controlthe migration of an LPAR to one of the other host systems using one ormore techniques for controlling migrations to other host systems.Depending on the type of virtualized computing environment in which ahost system is implemented, the host system may additionally oralternatively control migrations of different layers and groupings ofvirtualized components including applications, operating systems,workloads, and workload partitions.

In one example, application 104 may also submit resource request 106without specifying one or more performance parameters, and cede to oneor more of the performance parameters applied by operating system 108,hypervisor 120, or another host system to which application 104 ismigrated. For example, application 104 may be a legacy application thatdoes not have the functionality to specify performance parameters in aresource request or may not have the functionality to specifyperformance parameters for a selection of resources in a resourcerequest. For example, application 104 may submit resource request 106with a memory allocation request without any performance parameters thatonly specifies the size of the memory, such as a “malloc (size)”request. In one example, operating system 108 receives the “malloc(size)” request without any performance parameters specified and stillnegotiates on behalf of application 104 for memory of the “size”specified in the memory request, using the quality of serviceimplemented by operating system 108 or as applied by hypervisor 120. Inone example, where operating system 108 determines the quality ofservice for the “malloc(size)” request, operating system 108 maydetermine there is insufficient memory in a shared memory pool toallocate for the resource request, but operating system 108 may apply aquality of service policy for a performance trade-off, such as memorypaging, to satisfy the resource request. In another example, operatingsystem 108 may automatically require a highest quality of service forfulfilling a memory request, when the performance parameter is notspecified, and negotiate for real memory for application 104. In anotherexample, operating system 108 may cede to the quality of servicerequirements provided by hypervisor 120. In one example, hypervisor 120may apply a policy with a preference to migrate workloads within anensemble of host systems.

In contrast to the previous example of application 104 submittingresource request 106 of “malloc (size)” without any performanceparameters, as previously described with reference to resourcespecification and performance parameters 150, application 104 mayinitiate a negotiation for resources meeting performance parametersspecified by application 104, such as by submitting a request using thecommand “malloc (size=X bytes, lease start time=now, lease duration=24hours, quality of service=real memory, locality=anywhere, cost=10% cap,hidden)” where “lease start time, lease duration, quality of service,locality, and cost” are the performance parameters. In the example, the“quality of service” value specified in a memory allocation request mayspecify “real memory” to designate that memory paging is not acceptableand the “cost” value specified to “10% cap, hidden” may request a cap ofany increased cost for memory meeting the other parameters at a cap of10% of the regular fee and the “hidden” cost profile parameter mayspecify that the additional cap should be hidden from other hostsystems.

With reference now to FIG. 2, a block diagram illustrates one example ofa broker agent for managing negotiations for resources meetingperformance parameters in a virtualized computing environment. In oneexample, broker agent 126 is implemented in the hypervisor or othervirtual machine management layer.

In one example, broker agent 126 includes managed resource tables 202.Managed resource tables 202 may include tables or other data structuresfor managing the availability, use, location, reservations, and otheraspects of one or more resources available in a host system. In theexample, managed resource tables 202 include separate tables for each ofRAM 206 for managing the distribution of memory within the host system,including shareable memory, network bandwidth 208 for managing thedistribution of network resources within the host system, CPU(s) 210 formanaging the distribution of processors within the host system, storage212 for managing the distribution of disk space in the host system, CPUfrequency 214 for managing distribution of processors based on processorfrequency, power budget 216 for managing limits on power usage byapplications and logical partitions in the host system, and HW inventory218 for managing the hardware inventory files periodically stored from ascan of the hardware available in the host system.

In one example, broker agent 126 receives reservation requests from anoperating system of a logical partition, within the host system. Brokeragent 126 first maps the reservation request to the appropriate,particular table within managed resource tables 202. For example, if thereservation request is for a memory allocation, then broker agent 126maps the reservation request to RAM 206 within managed resource tables202. FIG. 3 illustrates one example of a reservation table entry for areservation request mapped to a particular table within managed resourcetables 202. In the example, a reservation table entry 302 is entered ina table appropriate for the type of resource being requested. Elementsof reservation table entry 302 may include, but are not limited to, anLPAR identifier (ID) identifying the LPAR of the operating systemsending the reservation request, a reservation start time and length, adesired quality of service (QoS), a locality limitation, and a costlimitation.

Next, broker agent 126 determines whether there are resources availablein the particular table within managed resource tables 202 that meet theperformance parameters in the reservation request and meet the policyrules of policy 220. FIG. 4 illustrates one example of the one or moretypes of policy rules that may be specified in policy 220. If brokeragent 126 determines there are resources available in the particulartable that meet the performance requirements in the reservation requestand that policy 220 allows use of the resources from the local hostsystem, then broker agent 126 reserves the resource for the requestinglogical partition and returns a reservation response to the operatingsystem of the requesting logical partition that the reservation has beengranted. The operating system returns a request response to therequesting application indicating that the request for resources hasbeen granted.

In the event that broker agent 126 determines there are not resourcesavailable locally, in the particular table, that meet the performancerequirements in the reservation request, then broker agent 126 may applypolicy 220 to determine what additional negotiations to perform. In oneexample, policy 220 may include, in service policy 404, a policy thatrequires broker agent 126, in the event that the locality specificationof a reservation request is specified as local, to still query costestimator 170 with a cost request or to query remote host systems with abid request, to determine whether to include a locality adjustment inalternate parameter recommendations 118. In another example, policy 220may include, in service policy 404, a policy that requires broker agent126, in the event that the locality specification of a reservationrequest is specified as local, to determine whether there is anotherLPAR in the host system, which if migrated, would free sufficientresources in managed resource tables 202 to provide sufficient localresources for a reservation request. If there is another LPAR in thehost system, which if migrated, would free sufficient resources, servicepolicy 404 may direct broker agent 126 to call cost estimator 170 orother host systems with a cost request for an estimated cost formigrating the other LPAR and a determination whether the migration iscost effective, or broker agent 126 may automatically broadcast a bidrequest to the other host systems.

In addition, if broker agent 126 determines there are not resourcesavailable locally and the locality setting of a reservation requestallows for remote resourcing, service policy 404 may specify that brokeragent 126 needs to broadcast a bid request to the other host systems. Inaddition, service policy 404 may further specify that broker agent 126first needs to select which LPAR within the host system to select forthe bid request, if there are other LPARs, which if migrated, would freesufficient resources in the host system to meet the resource requestrequirements and may also required that brokerage agent 126 submit costrequests for estimates of the cost of migrating each of the LPARs andselect which LPAR to submit bid requests on behalf of for migrationbased on the estimated costs for migrating each LPAR. In the example,other system map 224 includes a mapping of the locations of one or moreother host systems enabled to directly communicate through in apeer-to-peer management network. Broker agent 126 broadcasts a bidrequest for the reservation request to the other host systems accordingto other system map 224 and calls mediator 230 to manage the status andcollection of outgoing requests and incoming responses.

In one example, FIG. 5 illustrates a block diagram of a mediator 230that includes data structures for managing incoming communications 510and outgoing communications 530. In one example, outgoing communications530 may include a record of bid requests 534 broadcast by broker agent146 to multiple remote host systems requesting bids from the remote hostsystems for a reservation request and incoming communications 510 mayinclude a record of offers 518 including bid offers received from theremote host systems for migrating a reservation request.

In one example, a policy broker 540 of mediator 230 tracks a time wheneach separate bid request of bid requests 534 is broadcast and waits aparticular amount of time for collection of offers to each separate bidrequest of offers 518. Policy broker 540 collects all offers to a bidrequest and determines, based on workload, system preferences, and aremote selection policy 402 of policy 220, which responding remote hostsystem to select to receive a particular application. Factors that mayinfluence policy broker 540 in determining the best remote host systemfor a particular workload may include, but are not limited to, I/Orequirements of the application, including CPU, memory usage, networkbandwidth, and disk space requirements, power usage of the application,and hardware requirements, such as a particular adapter or hardwareaccelerator required for an application. Once broker agent 146 isapproved to accept a particular offer, broker agent 146 sends a bidacceptance, recorded in bid acceptances 536, and acts as the broker formigrating the requesting application to a remote host system.

In another example, broker agent 146 may broadcast a cost request,tracked in cost requests 532, to other remote host systems, where thecost request queries other remote host systems for an estimated cost ofwhat it would cost the other remote host systems to run an application,but is not a request for a remote host system place a bid committing toprovide resources for a particular application. Policy broker 540monitors for and records cost responses 516 from other remote hostsystems, responding to cost requests 532. In one example, broker agent146 may periodically query other remote host systems with cost requests532. In another example, broker agent 146 may query other remote hostsystems with cost request 532 when negotiating for resources for aparticular reservation request.

In one example, broker agent 146 may additionally or alternativelybroadcast a cost request, tracked in cost requests 532, to costestimator 170, where the cost request queries cost estimator 170 of thehost system for an estimated cost of what it would cost to migrate aparticular LPAR to one or more other host systems based on historicalcost data for previous LPAR migrations out of the host system to otherhost systems. Policy broker 540 may monitor for and collect costresponses 516 from cost estimator 170.

In addition, mediator 230 receives and records incoming communications510 from other remote host systems requesting costs, bids, and bidacceptances, including cost requests 512, bid requests 514, and bidacceptances 515, and mediator 230 records outgoing communications 530from the host system to one or more host systems including costresponses 538 and offers 539. For cost request 512 and bid requests 514,policy broker 540 queries broker agent 126 to determine a current costfor resources or to generate an offer to provide resources for areservation request. Broker agent 126 may call cost estimator 170 toestimate a cost for migrating a LPAR to the host system based onhistorical cost data for previous LPAR migrations into the host system.Broker agent 126 sends a response to the request to the requestingremote host system and mediator 230 records the response to the requestin cost responses 538 or offers 539. When policy broker 540 detects bidacceptances 515, policy broker 540 passes a reservation request tobroker agent 126 to reserve the resources for the remote host system.During the reservation lease time, hypervisor 120 receives a migrationof an application and moves the reserved resources to a logicalpartition hosting the application.

In particular, in one example, when policy broker 540 determines whichresponding remote host system to select to receive a particularapplication, policy broker 540 may apply remote selection policy 402 of“greedy” and spread the work evenly among the remote host systems thatdiscount costs to attract work from other host systems in other systemmap 224. In another example, application 104 may specify a “cost” inresource request 106 of “greedy”.

In addition, in one example, for policy broker 540 to assess costsassociated with migration, policy broker 540 may apply remote selectionpolicy 402 of “altruistic” and determine whether to give away oneapplication to satisfy the resource needs of another application. Inanother example, application 104 may specify a “cost” in resourcerequest 106 of “altruistic”. For example, if broker agent 126 needsresources for application B to run locally, but all or a portion of theneeded resources are in use locally by application A, the “altruistic”policy instructs broker agent 126 to send a cost query to remote hostsystems to estimate it would cost to run each of application A andapplication B. Policy broker 540 receives the cost estimations forrunning application A and application B remotely from the other hostsystems. Policy broker 540 may compare the sum cost of runningapplication A remotely and application B locally with the sum cost ofrunning application B remotely and application A locally and if the sumcost of running application B remotely and application A locally isgreater, then policy broker 540 may decide to give away application A tothe other host and broadcast an resource request for bids forapplication A, rather than application B, so that the local host systemresources used by application A will be freed up for use by applicationB. Once policy broker 540 determines which application to send to theremote host system, then policy broker 540 triggers broker agent 146 tobroadcast bid requests for the selected application to the remote hostsystems.

To apply the “altruistic” policy, policy broker 540 may request thatbroker agent 126 assess which applications within the host system, ifmigrated would free up sufficient resources for the requestingapplication, such as application B in the previous example, to runlocally. In addition, to apply the “altruistic” policy, policy broker540 may request that broker agent 126 assess which applications runningwithin the host system require a lower QoS from the requestingapplication and then determining whether migrating any of theseapplication would free up sufficient resources for the requestingapplication.

In the example, broker agent 126 may pass cost responses 516, offers518, cost responses 538, and offers 539 to cost estimator 170 forstorage in a history table. By storing cost responses and offers made bythe host system and received from other host systems, cost estimator 170maintains historical data about recent estimated and actual costs ofmigrating LPARs to and from a host system.

In the example, remote selection policy 402 and service policy 404specified in policy 220, for each host system, are modular andconfigurable, such that each host system may apply separate policies fordifferent types of resources and such that each host system may apply adifferent set of policies in policy 220 from any other host system in anensemble of host systems. By specifying policy 220 by resource and byhost system, each host system applies a set of policies specified forefficiently negotiating on behalf of applications based on anapplication initiated reservation request.

With reference now to FIG. 6, a block diagram illustrates one example ofa ensemble including multiple virtualized host systems, each managed bya separate hypervisor instance. In the example, ensemble 600 representsone type of virtualized computing environment, such as virtualizedcomputing environment 100, and includes a host system 502, remote hostsystem 650, and remote host system 660, communicatively connectedthrough management network 640. In one example, management network 640represents an established peer-to-peer network through which host system620, remote host system 650, and remote host system 660 directlycommunicate and through which a group of systems within ensemble 600 runwithout a central management entity. In one example, ensemble 500represents a pool of compatible host systems in which jobs can start onany host system, in which job workloads have mobility to beautomatically moved from and managed in one host system to another hostsystem, and in which each destination host system may volunteer to hostjob workloads.

In the example, host system 602 includes a hypervisor 630, remote hostsystem 650 includes a hypervisor 652, and remote host system 660includes a hypervisor 662. Each of hypervisor 630, hypervisor 652, andhypervisor 662 may perform one or more of the functions described withrespect to hypervisor 120, and in particular may each perform one ormore of the functions described with respect to broker agent 146. In theexample, hypervisor 630 includes a broker agent 632 for controllingnegotiations for resource reservations for logical partitions 604 and614. In the example, logical partitions 604 and 614, which are managedby a partition controller 634 of hypervisor 630 in host system 602, areillustrated. One of ordinary skill in the art will appreciate thatalthough not depicted, hypervisor 652 may manage at least one logicalpartition of remote host system 650 and hypervisor 662 may manage atleast one logical partition of remote host system 660.

In the example, LPAR 604 includes multiple applications, illustrated atreference numeral 606, resource management 608, a kernel 610 and anegotiation interface (NI) 612. Resource management 608 may include oneor more resource controllers, including memory management, which may beaccessed by hypervisor 630 for monitoring use of resources within LPAR604 and adjusting local records of resource allocations to LPAR 604.Kernel 610 may represent one instance of a guest operating system withinLPAR 604. Similarly, LPAR 614 includes multiple applications illustratedat reference numeral 616, resource management 618, kernel 620, andnegotiation interface 622.

In the example, negotiation interface 612 and negotiation interface 622perform at least one of the functions described with reference tonegotiation interface 110. For example, negotiation interface 612 mayreceive a resource request from application 624, format the resourcerequest into a reservation request, and pass the reservation request tobroker agent 632 of hypervisor 630. Broker agent 632 determines whetherthere are sufficient resources available for the reservation request onhost system 602. If there are not sufficient resources available for thereservation request on host system 602, broker agent 632 broadcasts acall for bids to remote host system 650 and remote host system 660through management network 640 and waits for offers from remote hostsystem 650 and remote host system 660 with bids for migration ofapplication 624 alone or LPAR 604, to the remote host system. Ifapplication 624 accepts a migration offer from one of the remote hostsystems, such as remote host system 650, then broker agent 632 managesthe migration to the reserved resources on remote host system 650.

As illustrated, negotiation interface 612 may receive resource requestsfrom multiple applications, however, the reservation requests sent bynegotiation interface 612 to hypervisor 630 may only identify LPAR 604,and not the individual application initiating the request. Negotiationinterface 612 may manage a table of outgoing requests indexed byapplication and upon receiving a response from hypervisor 630, match theresponse to the reservation request responded to, and identify theassociated requesting application.

In the example, if broker agent 632 applies an “altruistic” policy,then, in one example, if application 624 submits a resource request andthe resource request specifies resources that would be available locallyif not used by application 626, broker agent 632 may determine whetherit is more cost effective to migrate application 624, and thus LPAR 604,to one of remote host systems 650 and 660 or to migrate application 626,and thus LPAR 614, to one of remote host systems 650 and 660. In theexample, if broker agent 632 applies a “greedy” policy, then brokeragent 632 will evenly distribute work between remote host system 650 andremote host system 660, as each system is available to take work.

In another example, if locally satisfying a resource request byapplication 624 would cause an overcommitted state on host system 602,broker agent 632 may automatically initiate a partition migrationoperation for migrating LPAR 604 to one of remote host systems 650 and660. In one example, an overcommitted state may be caused by application624 requesting new memory pages that are not available in the memorycurrently allocated to LPAR 604 and additional memory is also notavailable within host system 602. In particular, policy 220 may includea setting that as soon as a host system cannot meet the memory needs ofa partition for a new memory page request, policy 220 requires that thepartition needs to be migrated. In one example, migration of LPAR 604may include starting the migration with the new pages that application624 requested and also using local swap space to store copies of localpages until the migration to a selected remote host, from among remotehost system 650 or 660, is complete.

In the example, partition controller 634 may control the partitionmigration operation for migrating LPAR 604 or LPAR 614 to one of remotehost systems 650 and 660 and may control the partition migrationoperation for migrating partitions into host system 602 from one ofremote host systems 650 and 660. In one example, partition controller634 controls communications between broker agent 632 and hypervisors 652and 622 and controls partition migration operations responsive to brokeragent 632 initiating partition migration operations. In controllingpartition migration operations, partition controller 634 may implementone or more different types of migration functions to handle differenttypes of migration scenarios and to optimize migration operations. Inone example, partition controller 634 may manage the memory allocations,memory sharing, and memory paging on host system 602 during a migrationof an LPAR to temporarily satisfy the memory requirements of anapplication while a partition migration occurs. In addition, whilepartition controller 634 is described with reference to migrating LPARs,in another embodiment, partition controller 634 may also migrateapplications, workloads, workload partitions, or other individual andgrouped virtualized components and partition controller 634 may alsomigrate virtualized components across multiple host systems.

With reference now to FIG. 7, a block diagram illustrates one example ofa broker agent managing local memory allocations and logical partitionmigrations, to provide memory meeting the quality of servicerequirements of one or more workloads. In the example, as illustrated atreference numeral 702, in a first system memory allocation, the memoryavailable in a host system is allocated between “LPAR 1”, “LPAR 2”, and“LPAR 3” or is available in as free memory. In the example, a workloadin “LPAR 3” requests a lease of memory for two hours and broker agent146 leases the memory to “LPAR 3” from the free memory, as illustratedat reference numeral 704. Next, in the example, a workload in “LPAR 2”requests additional memory and specifies a performance parameter of realmemory, but the request requires a memory allocation that that is largerthan the remaining free memory, which would result in an overallocation,as illustrated at reference numeral 706. Since broker agent 146determines that the additional memory required by “LPAR 2” is notavailable locally, and the requesting application in “LPAR 2” requiresreal memory and an altruistic cost, broker agent 146 determines whetherit is more cost effective to migrate “LPAR 2” to a remote host system orto migrate “LPAR 3” to a remote host system and free up the memoryleased to “LPAR 3”, to locally provide the memory required by “LPAR 2”.In the example, broker agent 146 determines that it is more costeffective to migrate “LPAR 2” to a remote host system and “LPAR 2”approves the offer to migrate to a remote host to receive the requestedreal memory.

FIG. 8 illustrates one example of a block diagram of a cost estimatorimplemented for estimating costs for migrating logical partitions basedon historical data captured from previous migrations of logicalpartitions. In the example, when broker agent 632 needs cost estimatesfor migration an LPAR to a remote host system, broker agent 632 submitscost estimate components 804 to cost estimator 170, where each of costestimate components 804 may specify one or more of a remote host systemand a target LPAR, for which cost estimates are requested. In addition,cost estimate components 804 may include requests for costs including,but are not limited to, network latency between systems, size of thepartition in a byte based measurement, size of the partition based onthe number of CPUs, and the rate at which the partition is touching anypages of memory. In one example, the rate at which the partition istouching any pages of memory effects migration latency because apartition that is touching a high number of pages will take longer tomigrate than a partition that is touching a lower number of pages. Costestimator 170 receives cost estimate components 804 and searches ahistory table 806 for records relevant to each of cost estimatecomponents 804.

In one example, history table 806 includes records of the costsassociated with migrations in and out of the host system, as illustratedat reference numeral 808. In one example, each record may include one ormore types of information including, but not limited to, a source ID ofthe host system, a destination ID of a remote host system, such as aremote host system 380 or a remote host system 832, and an LPAR ID of amigrating LPAR, as illustrated at reference numeral 810, migration costestimations 812, or migration actual costs 814. In one example,migration cost estimates 812 may include cost responses tracked bybroker agent 632 and migration actual costs 814 may include bid offerstracked by broker agent 632, where broker agent 632 formats and storescost responses and bid offers in history table 806 as illustrated atreference numeral 840, and actual migration costs 842 tracked bypartition controller 634 for migrations into and out of the host system.In one example, actual migration costs 842 may include the trackednetwork latency between systems for the migration, the amount of memoryor number of CPUs migrated, and other data indicating one or more typesof resource costs of migrating logical partitions between systems. Inone example, one or both of the target system partition controllertracks the actual migration costs of migrating an LPAR to the targetsystem. In another example, the source system partition controller mayreceive a communication from the target system partition controller atthe conclusion of an LPAR migration, where the closing communicationincludes the actual costs for migration of the LPAR, as tracked by thetarget system partition controller. In addition, migration costestimates 812 and migration actual costs 814 may include records fromdecoded LPAR migration headers by cost estimator 170 from incoming LPARmigrations, as illustrated by decoded LPAR migration header 828.

In one example, cost estimator 170 detects one or more records withinhistory table 806 that apply to current cost estimate components 804 andcost estimator 170 applies one or more of the policies specified inpricing and threshold policy 802 to prioritize the records and calculatean estimated cost for migrating an LPAR. In the example, cost estimator170 returns the estimated cost as cost estimate 808 to broker agent 632.In one example, broker agent 632 may submit cost estimate components 804for multiple LPAR migrations and compare cost estimate 808 returned foreach LPAR to estimate which LPAR may be the least expensive to migrateto a remote host system, such as remote host system 830 or remote hostsystem 832. As number complexity and size of a computing environmentgrows, the number of metrics applied by cost estimator 170 incalculating estimated costs and the weight given to each metric by costestimator 170 in calculating estimated costs is modular andconfigurable. For example, as the complexity and size of a computingenvironment grows, cost estimator 170 may apply a greater weight tonetwork latency costs in calculating the estimated costs of migrating anLPAR.

In one example, pricing and threshold policy 802 includes at least onepricing policy, where pricing policies may be specified for particularresources and specified for the particular host system. Examples ofpricing policies within pricing and threshold policy 802 may include,but are not limited to, an average pricing policy, an optimist pricingpolicy, and a pessimist pricing policy. Cost estimator 170 applies anaverage pricing policy by selecting the mean of the selection ofhistorical data identified in history table 806. Cost estimator 170applies an optimistic pricing policy by selecting the best case of theselection of historical data identified in history table 806. Costestimator 170 applies a pessimist pricing policy by selecting the worstcase of the selection of historical data identified in history table806.

In one example, when broker agent 632 selects to migrate an LPAR fromthe host system to one or remote host systems 830 or 832, broker agent632 directs partition controller 634 to control the migration of theselected LPAR. Partition controller 634 receives the LPAR migration calland calls cost estimator 170 with a request for a migration header forthe migrating LPAR. Cost estimator 170 receives migration headerrequests and searches history table 806 for a selection of the latestrelevant migration records for the target LPAR and the destinationremote host system. The number of latest relevant migration entriesselected may be specified for the type of resource, the LPAR, thedestination remote host system, or other searchable parameter. Costestimator 170 encodes a new migration data header 820 with the selectedmigration entries, identified by one or more of a source ID, adestination ID, or an LPAR ID, as illustrated at reference numeral 822,and returns the new migration data header to partition controller 634.In addition, cost estimator 170 deletes a selection of older entriesabout the LPAR based on a configured threshold number of entries tomaintain, as specified in pricing and threshold policy 802. Whenpartition controller 634 receives new migration data header 820 withhistorical cost data, for an LPAR migration, partition controller 634encodes the LPAR migration with the migration data header and begins themigrations of the LPAR to the selected destination remote host systemfrom among remote host systems 830 and 832. In addition, cost estimator170 may send a decoded LPAR migration header 828 of new LPAR migrationheader 820, for storage in history table 806, such that history table806 includes a record of the selected migration cost for the LPARmigration out of the host system.

In one example, when partition controller 634 receives migrations ofLPARs from one or more of remote host systems 830 and 832, partitioncontroller 634 the LPAR migration may include a migration data headerwith migration historical cost data. Partition controller 634 strips theLPAR migration header from incoming LPAR migrations and cost estimator170 decodes the LPAR migration header and sends a decoded LPAR migrationheader 828 to history table 806 for storage, such that history table 806includes a record of historical migration costs for LPAR migrations intothe host system.

In the example, by storing historical cost data for LPAR migrations outof and into a host system in history table 806, historical costinformation is available for cost estimator 170 to efficiently estimatea cost of migrating LPARs based on previous historical costs when brokeragent 632 requires cost estimates to determine which LPAR to attempt torequest migration bids for, from remote host systems. In the example, byincluding historical cost data for LPAR migrations in a migration dataheader with an LPAR migration, the historical cost data in history table806 is efficiently updated at the remote host system receiving amigration for use in estimated future migration costs.

In the embodiment illustrated, each host system in an ensemble,communicatively connected in the peer-to-peer network environment,implements a local cost estimator 170 and maintain a local history table806. In another embodiment, the host systems in an ensemble may access asingle system that hosts cost estimator 170 and history table 806 forthe ensemble.

FIG. 9 illustrates one example of a schematic of a computer system inwhich the present invention may be implemented. The present inventionmay be performed in a variety of systems and combinations of systems,made up of functional components, such as the functional componentsdescribed with reference to computer system 900 and may becommunicatively connected to a network, such as network 902. In oneexample, each of host system 602, remote host system 650, and remotehost system 660 may each implement one or more instances of functionalcomponents of computer system 900. In another example, computer system900 may represent one or more cloud computing nodes.

Computer system 900 includes a bus 922 or other communication device forcommunicating information within computer system 900, and at least onehardware processing device, such as processor 912, coupled to bus 922for processing information. Bus 922 preferably includes low-latency andhigher latency paths that are connected by bridges and adapters andcontrolled within computer system 900 by multiple bus controllers. Whenimplemented as a server or node, computer system 900 may includemultiple processors designed to improve network servicing power. Wheremultiple processors share bus 922, additional controllers (not depicted)for managing bus access and locks may be implemented.

Processor 912 may be at least one general-purpose processor such as IBM®PowerPC® (IBM and PowerPC are registered trademarks of InternationalBusiness Machines Corporation) processor that, during normal operation,processes data under the control of software 950, which may include atleast one of application software, an operating system, middleware, andother code and computer executable programs accessible from a dynamicstorage device such as random access memory (RAM) 914, a static storagedevice such as Read Only Memory (ROM) 916, a data storage device, suchas mass storage device 918, or other data storage medium. Software 950,including operating system and application software, may include, but isnot limited to, code, applications, protocols, interfaces, and processesfor controlling one or more systems.

In one embodiment, the operations performed by processor 912 may controlthe operations of flowchart of FIGS. 10, 11, and 12 and other operationsdescribed herein. Operations performed by processor 912 may be requestedby software, such as operating system and application software, or othercode or the steps of one embodiment of the invention might be performedby specific hardware components that contain hardwired logic forperforming the steps, or by any combination of programmed computercomponents and custom hardware components.

Those of ordinary skill in the art will appreciate that aspects of oneembodiment of the invention may be embodied as a system, method orcomputer program product. Accordingly, aspects of one embodiment of theinvention may take the form of an entirely hardware embodiment, anentirely software embodiment (including firmware, resident software,micro-code, etc.) or an embodiment containing software and hardwareaspects that may all generally be referred to herein as “circuit,”“module,” or “system.” Furthermore, aspects of one embodiment of theinvention may take the form of a computer program product embodied inone or more tangible computer readable medium(s) having computerreadable program code embodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk,such as mass storage device 918, a random access memory (RAM), such asRAM 914, a read-only memory (ROM) 916, an erasable programmableread-only memory (EPROM or Flash memory), an optical fiber, a portablecompact disc read-only memory (CDROM), an optical storage device, amagnetic storage device, or any suitable combination of the foregoing.In the context of this document, a computer readable storage medium maybe any tangible medium that can contain or store a program for use by orin connection with an instruction executing system, apparatus, ordevice.

A computer readable signal medium may include a propagated data signalwith the computer readable program code embodied therein, for example,in baseband or as part of a carrier wave. Such a propagated signal maytake any of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction executable system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to, wireless,wireline, optical fiber cable, radio frequency (RF), etc., or anysuitable combination of the foregoing.

Computer program code for carrying out operations of on embodiment ofthe invention may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Smalltalk, C++ or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on theuser's computer, such as computer system 900, partly on the user'scomputer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer or server. In the latter scenario, the remote computer may beconnected to the user's computer through any type of network, such asnetwork 902, through a communication interface, such as networkinterface 932, over a network link that may be connected, for example,to network 902.

In the example, network interface 932 includes an adapter 934 forconnecting computer system 900 to network 902 through a link. Althoughnot depicted, network interface 932 may include additional software,such as device drivers, additional hardware and other controllers thatenable communication. When implemented as a server, computer system 900may include multiple communication interfaces accessible via multipleperipheral component interconnect (PCI) bus bridges connected to aninput/output controller, for example. In this manner, computer system900 allows connections to multiple clients via multiple separate portsand each port may also support multiple connections to multiple clients.

One embodiment of the invention is described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodiments of theinvention. Those of ordinary skill in the art will appreciate that eachblock of the flowchart illustrations and/or block diagrams, andcombinations of blocks in the flowchart illustrations and/or blockdiagrams, can be implemented by computer program instructions. Thesecomputer program instructions may be provided to a processor of ageneral purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which execute via the processor of the computer orother programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

These computer program instructions may also be stored in acomputer-readable medium that can direct a computer, such as computersystem 900, or other programmable data processing apparatus to functionin a particular manner, such that the instructions stored in thecomputer-readable medium produce an article of manufacture includinginstruction means which implement the function/act specified in theflowchart and/or block diagram block or blocks.

The computer program instructions may also be loaded onto a computer,such as computer system 900, or other programmable data processingapparatus to cause a series of operational steps to be performed on thecomputer or other programmable apparatus to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

Network interface 932, the network link to network 902, and network 302may use electrical, electromagnetic, or optical signals that carrydigital data streams. The signals through the various networks and thesignals on network 902, the network link to network 902, and networkinterface 932 which carry the digital data to and from computer system900, may be forms of carrier waves transporting the information.

In addition, computer system 900 may include multiple peripheralcomponents that facilitate input and output. These peripheral componentsare connected to multiple controllers, adapters, and expansion slots,such as input/output (I/O) interface 926, coupled to one of the multiplelevels of bus 922. For example, input device 924 may include, forexample, a microphone, a video capture device, an image scanning system,a keyboard, a mouse, or other input peripheral device, communicativelyenabled on bus 922 via I/O interface 926 controlling inputs. Inaddition, for example, output device 920 communicatively enabled on bus922 via I/O interface 926 for controlling outputs may include, forexample, one or more graphical display devices, audio speakers, andtactile detectable output interfaces, but may also include other outputinterfaces. In alternate embodiments of the present invention,additional or alternate input and output peripheral components may beadded.

Those of ordinary skill in the art will appreciate that the hardwaredepicted in FIG. 9 may vary. Furthermore, those of ordinary skill in theart will appreciate that the depicted example is not meant to implyarchitectural limitations with respect to the present invention.

With reference now to FIG. 10, a high level logic flowchart depicts aprocess and program for managing application initiated negotiations forresources with a specified performance parameter. In the example, theprocess starts at block 1000 and thereafter proceeds to block 1002.

Block 1002 illustrates an application calling an operating system with aresource request for a particular resource and at least one performanceparameter. Next, block 1004 illustrates a determination whether aresponse is received to the resource request from the operating system.Once the application receives a response to the resource request, theprocess passes to block 1006. Block 1006 illustrates a determinationwhether a resource request is granted. If a resource request is granted,then the process passes to block 1018. Block 1018 illustrates markingthe request as granted and marking the location of the resource grant,whether local or remote, and the process ends.

Returning to block 1006, if a resource request is not granted, then theprocess passes to block 1008. Block 1008 illustrates a determinationwhether the response includes at least one of a remote offer andalternate options. If the response does not include at least one of aremote offer and alternate option, then the process passes to block1020. Block 1020 illustrates calling an error handler to handle thedeclined resource request, and the process ends.

Returning to block 1008, if the response does include at least one of aremote offer and alternate options, then the process passes to block1010. Block 1010 illustrates determining whether to accept the remoteoffer or adjust performance parameters of the resource request tocontinue negotiating. Next, block 1012 illustrates a determinationwhether the application accepts an offer. If the application accepts anoffer, then the process passes to block 1014. Block 1014 illustratescalling the operating system with an offer acceptance set, and theprocess passes to block 1018. Returning to block 1012, if theapplication does not accept an offer, then the process passes to block1016. Block 1016 illustrates calling the operating system with adjustedperformance parameters in the resource request, and the process returnsto block 1004.

With reference now to FIG. 11, a high level logic flowchart illustratesone example of a process and program for a negotiation interface of anoperating system managing application initiated negotiations forresources meeting performance parameters. In the example, the processstarts at block 1102, and thereafter proceeds to block 1104. Block 1104illustrates a determination whether a resource request call is receivedfrom an application. If a resource request call is received from anapplication, then the process passes to block 1106. Block 1106illustrates formatting the resource request into a reservation requestfor the hypervisor. Next, block 1107 illustrates recording thereservation request indexed by application identifier in an outgoingrequest table. Thereafter, block 1108 illustrates sending thereservation request to the hypervisor. Next, block 1110 illustrates adetermination whether the operating system receives a response to thereservation request. Once the operating system receives a response tothe reservation request, then the process passes to block 1112. Block1112 illustrates updating the status of the reservation request with theresponse. Next, block 1113 illustrates identifying the applicationidentifier assigned to the reservation request responded to in theoutgoing request table. Thereafter, block 1114 illustrates sending theresponse to the request application as a request response, and theprocess ends.

Referring now to FIG. 12, a high level logic flowchart illustrates oneexample of a process and program for a hypervisor managing two levels ofnegotiations for resources based on an application initiated negotiationfor resources meeting performance parameters specified by theapplication. In the example, the process starts at block 1200 andthereafter proceeds to block 1202. Block 1202 illustrates adetermination whether a hypervisor receives an application initiatedreservation request with performance parameters from an LPAR. If thehypervisor receives an application initiated reservation request withperformance parameters from an LPAR, then the process passes to block1204. Block 1204 illustrates negotiating to reserve at least oneavailable local resource in the host system that meets the performanceparameters for at least one resource specified in the reservationrequest. Next, block 1206 depicts a determination whether any localresource meeting the performance parameters is identified as availablefor reservation. If at least one local resource meeting the performanceparameters is identified as available, then the process ends. If nolocal resource meeting the performance parameters is identified asavailable for reservation, then the process passes to block 1208. Block1208 illustrates negotiating for offers to migrate the LPAR to a remotehost system with resources available that meet the performance parameterfor the at least one resource specified in the reservation request, andthe process ends.

Referring now to FIG. 13 a-13 b, a high level logic flowchartillustrates one example of a process and program for a broker agent of ahypervisor managing application initiated negotiations for local orremote resources meeting performance parameters specified by theapplication. In the example, the process starts at block 1300 andthereafter proceeds to block 1302. Block 1302 illustrates adetermination of whether the broker agent receives a reservation (res)request, with performance parameters, from a logical partition (LPAR).If the broker agent receives a reservation request, with performanceparameters, from an LPAR, then the process passes to block 1304. Block1304 illustrates mapping a reservation table entry for the reservationrequest to the appropriate resource table in the managed resourcetables. Next, block 1306 illustrates a determination whether there arelocally available resources in the mapped to resource table that satisfythe performance parameters of the reservation request. If there arelocally available resources in the mapped to resource table that satisfythe performance parameters of the reservation request, the processpasses to block 1308. Block 1308 illustrates reserving the availablelocal resources for the reservation request. Next, block 1310illustrates returning a response to the requesting LPAR that thereservation request is granted, and the process ends.

Returning to block 1306, if there are not locally available resourcesthat satisfy the performance parameters, then the process passes toblock 1312. Block 1312 illustrates a determination whether there iscurrently a local lease of the requested resource by another LPAR thatis migratable to a remote host system. In one example, an LPAR may bemigratable to a remote host system if the quality of service, cost, orlocality requirements of the LPAR allow for the LPAR to be migrated aremote host system. If there is not currently a local lease of therequested resource by another LPAR that is migratable, then the processpasses to block 1318. Block 1318 illustrates marking the requesting LPARas a migration candidate, and the process passes to block 1318.

Returning to block 1312, if there is currently a local lease of therequested resource by another LPAR that is migratable to a remote hostsystem, then the process passes to block 1314. Block 1314 illustratescollecting costs from remote host systems for handling the requestingLPAR and the other LPAR by calling the cost estimator with a costrequest or by calling the broker agent to broadcast a cost request tothe other host systems. Next, block 1316 illustrates a determinationwhether the estimated migration cost of the requesting LPAR is less thanthe estimated migration cost of the other LPAR. If the estimatedmigration cost of the requesting LPAR is less than the estimatedmigration cost of the other LPAR, then the process passes to block 1318.As previously described, block 1318 illustrates marking the requestingLPAR as a migration candidate, and the process passes to block 1322.Returning to block 1316, if the estimated migration cost of therequesting LPAR is not less than the estimated migration cost of theother LPAR, then the process passes to block 1320. Block 1320illustrates marking the other LPAR as a migration candidate, and theprocess passes to block 1322. By marking the other LPAR within a hostsystem as the migration candidate, the hypervisor next determineswhether the other LPAR can be migrated to a remote host system to makeroom locally for the fulfilling the resource request for the requestingLPAR.

Block 1322 illustrates broadcasting the LPAR reservation request for themigration candidate LPAR to the ensemble. Next, block 1324 illustrates adetermination of whether the broker agent receives responses with offersto migrate the LPAR from one or more remote host systems during awaiting period. If no offers are received during the waiting period,then the process passes to block 1338. Block 1338 illustrates returninga response to the requesting LPAR indicating that the reservationrequest is denied.

Returning to block 1324, if the broker agent receives responses withoffers from one or more remote host systems, then the process passes toblock 1326. Block 1326 illustrates a determination whether the brokeragent receives any offers that meet the performance parameters in thereservation request. If the broker agent determines that none of theoffers meet the performance parameters in the reservation requirement,then the process passes to block 1338. If the broker agent determinesthat at least one offer of the offers meets the performance parametersin the reservation requirement, then the process passes to block 1328.Block 1328 illustrates selecting the lowest cost bid from the offersmeeting the performance parameters. Next, block 1330 illustratesrequesting approval of the selected bids as an offer option from anapproving entity for the migration candidate, and the process passes toblock 1332. In one example, where the requesting LPAR is marked as themigration candidate, the approving entity may be the LPAR or thehypervisor. In another example, where the other LPAR is marked as themigration candidate, then the approving entity may be the hypervisor.

Block 1332 illustrates a determination whether the approving entityaccepts the migration offer for the LPAR marked as the migrationcandidate. If the approving entity does not accept the migration offer,then the process passes to block 1338. If the approving entity doesaccept the migration offer, then the process passes to block 1334. Block1334 illustrates sending a bid acceptance to the selected bidder hostsystem. Next, block 1336 illustrates calling the partition manager tobegin an LPAR migration of the LPAR marked as the migration candidate,to the selected bidder remote host system, and the process passes toblock 1340. Block 1340 illustrates a determination whether the otherLPAR is marked as the migration candidate. If the other LPAR is notmarked as the migration candidate, then the process ends. If the otherLPAR is marked as the migration candidate, then the process passes toblock 1342. Block 1342 illustrates reserving the resources freed fromthe migration of the other LPAR for the reservation request, and theprocess ends.

Referring now to FIG. 14, a high level logic flowchart illustrates aprocess and program for managing application initiated negotiations forresources from a legacy application or other application that does notspecify a performance parameter in a resource request. In the example,the process starts at block 1400 and thereafter proceeds to block 1402.Block 1402 illustrates an application calling an operating system with aresource request for a particular resource. In the example, theapplication calling the operating system with a resource request, incontrast to the example illustrated in block 1002 of FIG. 10, does notinclude a performance parameter in the resource request, for one ofmultiple reasons, such as the application being a legacy applicationthat does not include the functionality to specify a performanceparameter for any resource request, the application having thefunctionality to specify performance parameters for some resourcerequests but not all resource requests, or the application electing notto specify a performance parameter in the resource request. Next, block1404 illustrates a determination whether the requested resource isgranted by the operating system. If the requested resource is granted bythe operating system, then the process ends. If the requested request isnot granted by the operating system, then the process passes to block1406. Block 1406 illustrates calling an error handler, and the processends. In one example, an error handler called in block 1406 may performthe functions described in FIG. 10 starting at block 1020. In anotherexample, an error handler called in block 1406 may perform the processand program described in FIG. 10 starting at block 1008, where the errorhandler may read the response from an operating system to determinewhether the response includes a remote offer and alternate options. Inthe example in FIG. 14, for a legacy application or other applicationthat does not specify a performance parameter, the negotiation forresources described in FIGS. 11, 12, and 13 are still performed withinan ensemble of host systems, where an operating system, hypervisor, orother component may specify the performance parameter.

FIG. 15 illustrates a high level logic flowchart of a process andprogram for a partition controller receiving an LPAR migration andcalling a cost estimator with the migration history for the LPARmigration for storing in a cost estimator history table. In the example,a partition controller process starts at block 1500 and thereafterproceeds to block 1502. Block 1502 illustrates the partition controllerfor a host system determining whether an LPAR migration is received witha migration history header. If the partition controller receives an LPARmigration with a migration history header, then the process passes toblock 1504. Block 1504 illustrates stripping off the migration historyheader from the LPAR migration. Thereafter, block 1508 illustratescalling the cost estimator with the migration history header.

As illustrated, a cost estimator process starts at block 1510 andthereafter proceeds to block 1512. Block 1512 illustrates the costestimator determining whether an incoming migration history header callis received. If an incoming migration history header call is received,then the process passes to block 1514. Block 1514 illustrates decodingthe header to identify a source host system, a destination host system,a migrated LPAR identifier, estimated costs, and actual costs. Next,block 1516 illustrates storing the decoded header information in ahistory table. Thereafter, block 1518 illustrates deleting a selectionof old migration data for the identified LPAR from the history tablebased on a configured threshold, such as a threshold number of entriesabout the identified LPAR, and the process ends.

FIG. 16 illustrates a high level logic flowchart of a process andprogram for updating a history table with estimated and current costsfor logical partition migrations gathered during negotiations by abroker agent. In the example, a broker agent process starts at block1600 and thereafter proceeds to block 1602. Block 1602 illustrates thebroker agent determining whether new cost responses or offers aretracked by the mediator. If new cost responses or offers are tracked bythe mediator, then the process passes to block 1604. Block 1604illustrates decoding the cost responses or offers for a history tableformat. Next, block 1606 illustrates storing the decoded cost responsesor offers as records in a history table, and the process ends. Inanother example, a cost estimator or partition controller may performthe process and program described in FIG. 16.

FIG. 17 illustrates a high level logic flowchart of a process andprogram for a partition controller requesting migration header historyfor an LPAR to be migrated. In the example, a partition controllerprocess starts at block 1700 and thereafter proceeds to block 1702.Block 1702 illustrates the partition controller for a host systemdetermining whether a new LPAR migration from the host system to aremote system is in progress. If a new LPAR migration is in progress,then the process passes to block 1706. Block 1706 illustrates callingthe cost estimator with a migration header request with an LPAR ID forthe migrating LPAR and a destination ID for the remote host systemreceiving the migration. Next, block 1708 illustrates a determinationwhether a migration data header is received from the cost estimator. Ifa migration data header is received from the cost estimator, then theprocess passes to block 1710. Block 1710 illustrates encoding the LPARmigration with the migration data header, and the process ends.

As illustrated, a cost estimator block starts at block 1712 andthereafter proceeds to block 1714. Block 1714 illustrates adetermination whether a migration header request is received. If amigration header request is received, then the process passes to block1716. Block 1716 illustrates selecting the N-latest relevant migrationentries from the history table for the LPAR ID or the destination ID,where N is a value configured for the host system. Next, block 1718illustrates encoding the new migration data header with the selectedmigration entries, LPAR ID, source ID for the host system, anddestination ID for the remote host system. Thereafter, block 1720illustrates returning the new migration data header to the partitioncontroller. Next, block 1722 illustrates deleting a selection of oldesttable entries about the LPAR based on a configured threshold, such as athreshold number of LPAR entries to be stored, and the process ends.

FIG. 18 illustrates a high level logic flowchart of a process andprogram for a cost estimator estimating the cost for migration of anLPAR. In the example, the cost estimator process starts at block 1800and thereafter proceeds to block 1802. Block 1802 illustrates adetermination the cost estimator receives a cost estimate request. Ifthe cost estimator receives a cost estimate request, then the processpasses to block 1804. Block 1804 illustrates searching the history tablefor migration entries to or from the remote host system and entriesabout the target LPAR. Next, block 1806 illustrates a determinationwhether the cost estimator identifies any actual data for the remotehost system or the target LPAR. At block 1806, if the cost estimatordoes not find any actual data, then the process passes to block 1820.Block 1820 illustrates the cost estimator selecting the mean ofhistorical data for other LPARS or selecting pre-configured defaultdata, and the process passes to block 1816.

Returning to block 1806, if the cost estimator finds data, then theprocess passes to block 1808. Block 1808 illustrates the cost estimatordetermining which pricing policy to apply for the host system.

At block 1808, if the cost estimator determines that the average (avg)pricing policy applies, then the process passes to block 1810. Block1810 illustrates selecting the mean pricing of the historical data foundfor the remote host system or target LPAR, and the process passes toblock 1816.

Returning to block 1808, if the cost estimator determines that theoptimist pricing policy applies, then the process passes to block 1812.Block 1812 illustrates selecting the best case pricing the historicaldata found for the remote host system or target LPAR, and the processpasses to block 1816.

Returning to block 1808, if the cost estimator determines that thepessimist pricing policy applies, then the process passes to block 1814.Block 1814 illustrates selecting the worst case pricing of thehistorical data found for the remote host system or target LPAR, and theprocess passes to block 1816.

Block 1816 illustrates calculating the migration cost based on theselected historical data. Next, block 1818 illustrates returning thecalculated migration cost as a cost estimate, and the process ends.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, occur substantiallyconcurrently, or the blocks may sometimes occur in the reverse order,depending upon the functionality involved. It will also be noted thateach block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising”, when used in this specification specify thepresence of stated features, integers, steps, operations, elements,and/or components, but not preclude the presence or addition of one ormore other features, integers, steps, operations, elements, components,and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the one or more embodiments of the invention has beenpresented for purposes of illustration and description, but is notintended to be exhaustive or limited to the invention in the formdisclosed. Many modifications and variations will be apparent to thoseof ordinary skill in the art without departing from the scope and spiritof the invention. The embodiment was chosen and described in order tobest explain the principles of the invention and the practicalapplication, and to enable others of ordinary skill in the art tounderstand the invention for various embodiments with variousmodifications as are suited to the particular use contemplated.

While the invention has been particularly shown and described withreference to one or more embodiments, it will be understood by thoseskilled in the art that various changes in form and detail may be madetherein without departing from the spirit and scope of the invention.

What is claimed is:
 1. A method for managing requests for resources,comprising: responsive to a hypervisor determining that insufficientlocal resources are available for reservation to meet a performanceparameter for at least one resource specified in a reservation requestfor a particular logical partition managed by the hypervisor in a hostsystem, identifying another logical partition managed by the hypervisorin the host system that is assigned at the least one resource meetingthe performance parameter specified in the reservation request;estimating, by the hypervisor, a first cost of migrating the particularlogical partition and a second cost of migrating the another logicalpartition to at least one other host system communicatively connected ina peer-to-peer network based on at least one previously recorded coststored by the host system of migrating a previous logical partition tothe at least one other host system; selecting, by the hypervisor, one ofthe particular logical partition and the another logical partition as amigration candidate based on a comparison of the first cost with thesecond cost, wherein the hypervisor negotiates for offers to migrate themigration candidate to the at least one other host system; responsive toselecting a remote host system from among the at least one other hostsystem to migrate the migration candidate to, calling, by thehypervisor, a cost estimator of the host system to create a migrationheader; selecting, by the cost estimator, a selection of most recentpreviously recorded migration costs by the host system for a targetlogical partition and for the remote host system; encoding, by the costestimator, a migration data header with the selection of most recentpreviously recorded migration costs; and encoding, by the hypervisor,the migration candidate with the migration data header, wherein theremote host system receives the migration candidate with the migrationdata header, removes the migration data header from the migrationcandidate, and records the selection of most recently previous recordedmigration costs for the target logical partition and for the remote hostsystem for estimating the cost of migrations from the remote hostsystem.
 2. The method according to claim 1, wherein estimating, by thehypervisor, a first cost of migrating the particular logical partitionand a second cost of migrating the another logical partition to at leastone other host system based on at least one previously recorded coststored by the host system of migrating a previous logical partition tothe at least one other host system further comprises: identifying aplurality of previously recorded costs for migrations to the at leastone other host system; identifying a pricing policy applied by the hostsystem; responsive to the host system applying an average pricingpolicy, selecting a mean cost of the plurality of previously recordedcosts to estimate the first cost and the second cost; responsive to thehost system applying an optimist pricing policy, selecting a best casecost of the plurality of previously recorded costs to estimate the firstcost and the second cost; and responsive to the host system applying apessimist pricing policy, selecting a worst case cost of the pluralityof previously recorded costs to estimate the first cost and the secondcost.
 3. The method according to claim 1, further comprising:negotiating, by the hypervisor, to reserve at least one available localresource in the host system that meets the performance parameter for theat least one resource specified in the reservation request by theparticular logical partition from among a plurality of logicalpartitions of virtualized pools of resources managed by the hypervisorin the host system, wherein the at least one performance parameter isspecified by a particular application initiating the reservation requestfrom the particular logical partition; and responsive to determiningthat the at least one available resource is not available in the hostsystem, negotiating, by the hypervisor, for offers to migrate themigration candidate to the at least one other host system, wherein theat least one other host system is managed by at least one otherhypervisor that manages one or more other logical partitions ofvirtualized pools of resources.
 4. The method according to claim 1,further comprising: broadcasting a request for bids for migrating themigration candidate to the at least one other host systemcommunicatively connected without a central management device in thepeer-to-peer network; responsive to receiving at least one offer from atleast one of the at least one other host system, selecting a particularoffer from among the at least one offer from a selected remote hostsystem from among the at least one other host system; migrating themigration candidate logical partition to the selected remote host systemvia the peer-to-peer network; and responsive to migrating the anotherlogical partition marked as the migration candidate, reserving at leastone freed resource previously assigned to the another logical partitionfor satisfying the reservation request for the particular logicalpartition.
 5. A logically partitioned host system having a plurality oflogical partitions of pools of virtualized resources and an operatingsystem operating in each of the logical partitions, comprising: ahypervisor operative on the host system, wherein the host systemcomprises at least one memory and at least one processor coupled to thememory, to manage the plurality of logical partitions of pools ofvirtualized resources and operative, responsive to determining thatinsufficient local resources are available for reservation to meet aperformance parameter for at least one resource specified in areservation request for a particular logical partition managed by thehypervisor in the host system, to identify another logical partitionfrom among the plurality of logical partitions that is assigned the atleast one resource meeting the performance parameter specified in thereservation request; the hypervisor operative to estimate a first costof migrating the particular logical partition and a second cost ofmigrating the another logical partition to at least one other hostsystem communicatively connected in a peer-to-peer network based on atleast one previously recorded cost stored by the host system ofmigrating a previous logical partition to the at least one other hostsystem; and the hypervisor operative to select one of the particularlogical partition and the another logical partition as a migrationcandidate based on a comparison of the first cost with the second cost,wherein the hypervisor negotiates for offers from the at least one otherhost system to migrate the migration candidate to the at least one otherhost system; the hypervisor, responsive to selecting a remote hostsystem from among the at least one other host system to migrate themigration candidate to, operative to call a cost estimator of the hostsystem to create a migration header; the cost estimator operative toselect a selection of most recent previously recorded migration costs bythe host system for a target logical partition and for the remote hostsystem; the cost estimator operative to encode a migration data headerwith the selection of most recent previously recorded migration costs;and the hypervisor operative to encode the migration candidate with themigration data header, wherein the remote host system receives themigration candidate with the migration data header, removes themigration data header from the migration candidate, and records theselection of most recently previous recorded migration costs for thetarget logical partition and for the remote host system for estimatingthe cost of migrations from the remote host system.
 6. The logicallypartitioned host system according to claim 5, further comprising: apartition controller of the hypervisor, responsive to receiving alogical partition migration with a migration data header, operative toremove the migration data header from the logical partition migration; acost estimator of the host system operative to decode the migration dataheader into at least one identifier of at least one of a source hostsystem, a destination host system, and a logical partition and at leastone cost of at least one of an estimated cost and an actual cost; andthe cost estimator operative to store the decoded migration data headerin a history table comprising a plurality of records of migration costsfor at least one migration from the host system to at least one of theat least one other host system and the at least one previously recordedmigration cost.
 7. The logically partitioned host system according toclaim 5, further comprising: the hypervisor operative to identify the atleast one previously recorded migration cost for migrations to the atleast one other host system from a history table; the hypervisoroperative to identify a pricing policy applied by the host system; thehypervisor, responsive to the host system applying an average pricingpolicy, operative to select a mean cost of the at least one previouslyrecorded migration cost to estimate the first cost and the second cost;the hypervisor, responsive to the host system applying an optimistpricing policy, operative to select a best case cost of the at least onepreviously recorded migration cost to estimate the first cost and thesecond cost; and the hypervisor, responsive to the host system applyinga pessimist pricing policy, operative to select a worst case cost of theat least one previously recorded migration cost to estimate the firstcost and the second cost.
 8. The logically partitioned host systemaccording to claim 5, further comprising: the hypervisor operative tonegotiate to reserve at least one available local resource in the hostsystem that meets the performance parameter for the at least oneresource specified in the reservation request by the particular logicalpartition from among a plurality of logical partitions of virtualizedpools of resources managed by the hypervisor in the host system, whereinthe at least one performance parameter is specified by a particularapplication initiating the reservation request from the particularlogical partition; and the hypervisor, responsive to determining thatthe at least one available resource is not available in the host system,operative to negotiate for offers to migrate the migration candidate tothe at least one other host system, wherein the at least one other hostsystem is managed by at least one other hypervisor that manages one ormore other logical partitions of virtualized pools of resources.
 9. Thelogically partitioned host system according to claim 5, furthercomprising: the hypervisor operative to broadcast a request for bids formigrating the migration candidate to the at least one other host system;the hypervisor, responsive to receiving at least one offer from at leastone of the at least one other host system, operative to select aparticular offer from among the at least one offer from a selectedremote host system from among the at least one other host system; thehypervisor operative to migrate the migration candidate logicalpartition to the selected remote host system; and the hypervisor,responsive to migrating the another logical partition marked as themigration candidate, operative to reserve at least one freed resourcepreviously assigned to the another logical partition for satisfying thereservation request for the particular logical partition.
 10. A computerprogram product for managing requests for resources, said computerprogram product tangibly embodied in a computer-readable storage medium,wherein the computer-readable storage medium is not a transitory signalper se, and comprising computer executable instructions which cause acomputer to: responsive to a hypervisor determining that insufficientlocal resources are available for reservation to meet a performanceparameter for at least one resource specified in a reservation requestfor a particular logical partition managed by the hypervisor in a hostsystem, identify another logical partition managed by the hypervisor inthe host system that is assigned at the least one resource meeting theperformance parameter specified in the reservation request; estimate, bythe hypervisor, a first cost of migrating the particular logicalpartition and a second cost of migrating the another logical partitionto at least one other host system based on at least one previouslyrecorded cost stored by the host system of migrating a previous logicalpartition to the at least one other host system; select, by thehypervisor, one of the particular logical partition and the anotherlogical partition as a migration candidate based on a comparison of thefirst cost with the second cost, wherein the hypervisor negotiates foroffers to migrate the migration candidate to the at least one other hostsystem; responsive to selecting a remote host system from among the atleast one other host system to migrate the migration candidate to, call,by the hypervisor a cost estimator of the host system to create amigration header; select, by the cost estimator, a selection of mostrecent previously recorded migration costs by the host system for atarget logical partition and for the remote host system; encode, by thecost estimator, a migration data header with the selection of mostrecent previously recorded migration costs; and encode, by thehypervisor, the migration candidate with the migration data header,wherein the remote host system receives the migration candidate with themigration data header, removes the migration data header from themigration candidate, and records the selection of most recently previousrecorded migration costs for the target logical partition and for theremote host system for estimating the cost of migrations from the remotehost system.
 11. The computer program product according to claim 10,further comprising computer executable instructions which cause acomputer to: identify a plurality of previously recorded costs formigrations to the at least one other host system; identify a pricingpolicy applied by the host system; responsive to the host systemapplying an average pricing policy, select a mean cost of the pluralityof previously recorded costs to estimate the first cost and the secondcost; responsive to the host system applying an optimist pricing policy,select a best case cost of the plurality of previously recorded costs toestimate the first cost and the second cost; and responsive to the hostsystem applying a pessimist pricing policy, select a worst case cost ofthe plurality of previously recorded costs to estimate the first costand the second cost.